Method for machining a sheet-metal profile

ABSTRACT

The invention relates to a method for machining a sheet-metal profile  1 , wherein the sheet-metal profile  1  is trimmed in a multi-stage cutting process and a cutting edge  2  is produced. Here, pre-cutting is firstly performed on the sheet-metal profile  1 , whereby a free space  3  is generated. Stamping of the sheet-metal profile  1  is subsequently performed, wherein the thickness d of the sheet-metal profile  1  along the cutting edge  2  to be produced is reduced. Subsequently, the cutting finishing of the sheet-metal profile  1  is performed, wherein, in particular, cutting is performed in the opposite direction to the stamping of the outline of the finished contour, and the cutting edge  2  is generated.

RELATED APPLICATIONS

The present application claims priority of German Application Number 10 2018 106 520.5 filed Mar. 20, 2018, the disclosure of which is hereby incorporated by reference herein in its entirety.

FIELD

The disclosure relates to a method for machining a sheet-metal profile, wherein the sheet-metal profile is trimmed in a multi-stage cutting process.

BACKGROUND

In the deformation of metal sheets, shear cutting is an established technique. In this method, a characteristic roughness and a burr are formed, because short cut and relatively long break portions form at the cutting edge. These reduce the capability of the components or sheet-metal profiles to withstand expansions or fluctuating loads.

Another method is countercutting. Here, the sheet-metal profile is, in a first step, subjected to initial cutting on a first side at the desired cut edge. In the second step, a second cutting punch is used from the opposite side. Said cutting punch then severs the metal in the opposite direction. As a result of the first stamping or initial cutting, a material accumulation forms on the opposite side, whereby the second cutting punch does not make contact in the correct manner with the metal sheet to be cut. As a result, the desired intense increase of the cut stress at the cut edge does not arise.

DE 1 0 2008 028 242 A1 describes a method and a device for the sheer cutting of sheet-metal components. Here, before the shear cutting, the sheet-metal component is locally warmed in the region of the cut edge by means of a laser beam in order to lower the hardness. In this way, the cutting tool is preserved, in the case of press-hardened steels.

The prior art also includes a method for producing a sheet-metal molded part as per DE 10 2005 051 403 B3. In said document, before or during the hot working, a stamping is introduced into cut zones in the workpiece, which stamping reduces the wall thickness in the cut zone. After the hot working, trimming is performed on the hardened component within the stamping. This measure also contributes to facilitating the trimming, like hard cutting, or making this possible in the first place.

Within the scope of WO 2013/167232 A1, a method for dividing up a workpiece is disclosed, and a device suitable for this purpose is specified. Here, into the workpiece to be divided up, a notch geometry is introduced at least on one side along a parting line with plastic deformation, which notch geometry ends in the workpiece, and the workpiece is subjected to shear cutting along the parting line. It is sought in this way to generate a burr-free cut or break surface.

In the method discussed in WO 02/081116 A1, it is the intention for burr-free cutting of metal sheets to be performed by virtue of the metal sheet initially being merely pressed along the desired cut line by means of a stamping punch and a stamping die without relative bending thereof so as to form a step in a first direction, and only then being fully severed using a cutting punch and a cutting die in the opposite direction. A cutting gap is present between the cutting punch and the cutting die. The stamping punch and the stamping die are intended to overlap one another with the aim of pressing the metal sheet along the desired cutting line to an only small residual thickness. By means of the small residual thickness, it is then possible in the second method step for a relatively large cutting gap to be set between the cutting punch and the cutting die, whereby it is sought to reduce the risk of collision between the cutting punch and the cutting die.

Within the scope of JP 2008 229710 A, the formation of holes in a blank is discussed. Here, circular stamping using a first punch is performed, following which a second punch with a smaller diameter than the stamping is used to punch the hole in the opposite direction. This involves countercutting.

A similar approach is also disclosed in EP 2 062 664 B1.

JP H06-344 049 A discloses a method in which pre-cutting is performed on a sheet-metal profile, whereby a free space is generated. Subsequently, stamping of the sheet-metal profile is performed, wherein the thickness of the sheet-metal profile along the cutting edge to be produced is reduced. Subsequently, the cutting finishing of the sheet-metal profile is performed, wherein the cutting edge is generated.

SUMMARY

The disclosure is based on the object of specifying a method for machining a sheet-metal profile, in which the sheet-metal profile is trimmed and a burr-free cutting edge which can be subjected to static and dynamic loading is produced, wherein the method can be integrated into a standard deformation process.

In the method according to one or more embodiments of the disclosure for machining a sheet-metal profile, the sheet-metal profile is trimmed in a multi-stage cutting process, wherein a cutting edge is produced. For this purpose, pre-cutting is firstly performed on the sheet-metal profile, whereby a free space is generated. Stamping of the sheet-metal profile is subsequently performed, wherein the thickness of the sheet-metal profile along the cutting edge to be produced is reduced. Subsequently, the cutting finishing of the sheet-metal profile is performed, wherein the cutting edge is generated. Here, the outline of the finished contour is cut.

The method according to one or more embodiments of the disclosure can be applied to different sheet-metal profiles and various components, for example structural components (for example transverse connectors) or chassis components (for example torsional profiles, links).

In the context of one or more embodiments of the disclosure, a sheet-metal profile is to be understood to mean both a planar sheet-metal blank and also a pre-shaped sheet-metal blank, a semifinished part or a shaped molded component. The sheet-metal profile is made of metal, like steel or of light metal.

Compared to known approaches, the edges of the workpiece or of the sheet-metal profile are rounded, and there is no burr. A sheet-metal profile is provided which has a burr-free cutting edge which can be subjected to high static and dynamic loading. By means of the absence of burrs on both sides at the one or more cutting edges, the service life of the components is greatly improved. Furthermore, the assembly of such sheet-metal profiles, or of components produced therefrom, is improved. By contrast to shear cutting, the rough break zone is relocated into the middle part which is subjected to lower stresses, and is additionally reduced. The cutting edge produced according to one or more embodiments of the disclosure withstands greater expansions, whereby no cracks form in the event of further deformations. Greater numbers of dynamic load alterations can also be withstood.

According to one or more embodiments of the disclosure, the stamping and cutting finishing are performed in opposite directions, that is to say the direction of action during the stamping and the direction of action during the cutting finishing are from opposite sides in relation to the plane of the sheet-metal profile.

The pre-cutting and the stamping in one or more embodiments are also performed in opposite directions.

The pre-cutting is performed along a pre-cutting edge. The pre-cutting edge has a spacing to the cutting edge to be produced, that is to say the final cutting edge. The spacing is dimensioned to be between 30% and 75% of the sheet-metal thickness. This means that the spacing of the pre-cutting edge to the cutting edge to be produced lies between 0.3 and 0.75 times the sheet-metal thickness. The spacing amounts to 40% to 60% of the sheet-metal thickness. A spacing between 45% and 55% of the sheet-metal thickness is considered to be suitable for practical purposes. In at least one embodiment provides for the spacing of the pre-cutting edge to the final cutting edge to be 50% of the sheet-metal thickness of the sheet-metal profile. This means that the spacing amounts to 0.5 times the sheet-metal thickness.

A further aspect of the disclosure provides for the thickness of the sheet-metal profile to be reduced by 15% to 50%, or by 20% to 40%, during the stamping. A reduction of the sheet-metal thickness by 30%, that is to say by 0.3 times the sheet-metal thickness.

During the stamping, the material in the region of the stamping zone is plastically deformed or stamped between the pre-cutting edge and the cutting edge to be produced. The material in the stamping zone to be is molded into the free space substantially at right angles, that is to say at 90°, with respect to the stamping direction. This measure assists the subsequent cutting finishing.

As already mentioned, the cutting process according to one or more embodiments of the disclosure can be integrated into a standard deformation process. Accordingly, the sheet-metal profile can be deformed before, during or after the cutting process.

With the method according to one or more embodiments of the disclosure for machining a sheet-metal profile, and the cutting process used here, the formation of a cut burr can be avoided. Finish machining processes formed after the cutting process in order to remove cut burrs can be omitted, or are substantially minimized. Grinding inspections of the cutting edges produced according to one or more embodiments of the disclosure have shown that outer smooth cut portions with cutting edges almost at right angles are obtained.

The method according to one or more embodiments of the disclosure is in regard to processing times, productivity and also energy efficiency. The method and the sheet-metal profiles or molded components produced in accordance with the method are distinguished by their cut surface quality.

In the machining of the sheet-metal profile and the cutting process according to one or more embodiments of the disclosure, it is possible to produce closed cutting edges or cut lines and open cutting edges or cut lines. With the cutting process, it is possible to perform both hole formation and trimming, cutting-out or notching on a sheet-metal profile.

The disclosure will be described in more detail below on the basis of at least an exemplary embodiment illustrated in the drawings. FIGS. 1 to 3 illustrate three method stages of a cutting process on a sheet-metal profile.

BRIEF DESCRIPTION OF THE DRAWINGS

For an understanding of embodiments of the disclosure, reference is now made to the following description taken in conjunction with the accompanying drawings, in which:

FIG. 1 shows the pre-cutting of a sheet-metal profile;

FIG. 2 shows the subsequent stamping at the cut contour of the sheet-metal profile, and

FIG. 3 shows the cutting finishing of the sheet-metal profile.

In the figures, the same reference numerals are used for identical or similar components, even though a repeated description is omitted for reasons of simplification.

DETAILED DESCRIPTION

The method according to one or more embodiments of the disclosure for machining a sheet-metal profile 1 includes a three-stage cutting process for generating at least one cutting-edge 2, in the course of the production of holes, recesses and similar trimming contours on the sheet-metal profile 1. A sheet-metal profile 1 may be a planar sheet-metal blank, a preformed sheet-metal blank, a semifinished part or a fully shaped molded component, composed in each case of metal.

The cutting process comprises the process steps:

-   -   pre-cutting (in this regard, see FIG. 1),     -   stamping (in this regard, see FIG. 2), and     -   cutting finishing (in this regard, see FIG. 3).

Pre-cutting: to create a free space 3 for the subsequent “stamping” operation, trimming is performed, using standard methods, with a spacing a of 0.5 times the sheet-metal thickness d in relation to the (final) cutting edge 2 to be produced.

Stamping: the outline of the finished contour is stamped to a depth of 0.3 times the sheet-metal thickness. The displaced material flows in this case at an angle of 90° into the free space 3 produced previously. No accumulations of material form.

Cutting finishing: in the opposite direction to the stamping, the outline of the finished contour is now cut on the sheet-metal profile 1, wherein the cutting edge 2 is generated.

The stamping and the cutting finishing are performed in opposite directions. The directions of action are indicated in FIGS. 2 and 3 by the arrows P and F.

The pre-cutting and the stamping are also performed in opposite directions. This is illustrated in FIGS. 1 and 2 by the labeling of the directions of action using the arrows V and P.

During the pre-cutting, the sheet-metal profile 1 is clamped between a lower tool part 4 and an upper tool part 5. The pre-cutting is performed by means of a pre-cutting punch 6. For the pre-cutting, the pre-cutting punch 6 is, in the plane of the image of FIG. 1, moved from top to bottom in accordance with the arrow V. Here, a portion 8 is separated out of the sheet-metal profile 1 along a pre-cutting-edge 7.

The pre-cutting-edge 7 is situated with a spacing (a) to the cutting edge 2 to be produced. The spacing a amounts to 0.5 times the sheet-metal thickness d, that is to say 50% of the sheet-metal thickness. It is basically possible for the spacing to be dimensioned to be between 30% and 75%, between 40% and 60%, or between 45% and 55%, of the sheet-metal thickness (d).

During the stamping, the pre-cut sheet-metal profile 1 is fixed between the lower tool part 4 and an upper counterholder 9. The stamping is performed using a stamping tool 10 which, in the plane of the image, is moved from bottom to top in accordance with the arrow P. Here, the stamping zone 11 between the pre-cutting edge 7 and the cutting edge 2 to be produced is stamped, that is to say the outline of the finished contour is stamped to a depth of 0.3 times the sheet-metal thickness d. Here, the displaced material flows into the free space 3 substantially at right angles, or at an angle of 90° with respect to the stamping direction or direction of action P.

As discussed above, the outline of the finished contour and the thickness d of the sheet-metal profile 1 is reduced during the stamping by 0.3 times the sheet-metal thickness d, that is to say 30%. In practice, depending on the sheet-metal profile 1 and the cut contour or cutting edge 2 to be produced, a reduction of the thickness d by 15% to 50%, or between 20% and 40%, may be performed.

During the cutting finishing, the sheet-metal profile 1 is clamped between the lower tool part 4 and an upper tool part 12. The upper tool part 12 may also be the upper tool part 5 or the upper counterholder 9 as illustrated in FIG. 1 or FIG. 2. For the cutting process for the cutting finishing, the upper tool part 5 or the upper counterholder 9 is then displaced into the component-specific cutting finishing position. The cutting finishing is performed using a cutting punch 13 which, in the plane of the image of FIG. 3, moves from top to bottom in accordance with the arrow F. Here, the stamped material of the stamping zone 11 is separated off from the sheet-metal profile 1 along the cutting edge 2.

The method according to the disclosure for producing a cut edge 2 on or in a sheet-metal profile 1 leads to high cut surface quality. The cutting process can also be integrated into a deformation process. It is therefore possible for the sheet-metal profile 1 to be deformed before, during or after the cutting process.

The foregoing description of some embodiments of the disclosure has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure to the precise form disclosed, and modifications and variations are possible in light of the above teachings. The specifically described embodiments explain the principles and practical applications to enable one ordinarily skilled in the art to utilize various embodiments and with various modifications as are suited to the particular use contemplated. It should be understood that various changes, substitutions and alterations can be made hereto without departing from the spirit and scope of the disclosure. 

1-6. (canceled)
 7. A process of machining a sheet-metal profile, the process comprising: trimming the sheet-metal profile in a multi-stage cutting process forming a cutting edge, pre-cutting a free space in the sheet-metal profile, stamping of the free space formed in the precutting of the sheet-metal profile, wherein a thickness of the sheet-metal profile along the cutting edge is reduced by the stamping, and cutting finishing the sheet-metal profile, wherein the cutting edge is formed such that the stamping and the cutting finishing are performed in opposite directions.
 8. A process according to claim 7, wherein the pre-cutting and the stamping are performed in opposite directions.
 9. A process according to claim 7, wherein the pre-cutting is performed along a pre-cutting edge, wherein the pre-cutting edge has a spacing to the cutting edge, which spacing is dimensioned to be between 30% and 75% of the thickness of the sheet-metal profile.
 10. A process according to claim 7, wherein the thickness of the sheet-metal profile is reduced by 15% to 50%, due to the stamping.
 11. A process according to claim 7, wherein during the stamping, a portion of the sheet-metal profile in a stamping zone is molded into the free space substantially at right angles with respect to the stamping direction.
 12. A process according to claim 7, wherein the sheet-metal profile is deformed before, during and after the cutting process.
 13. A process according to claim 7, wherein the thickness of the sheet-metal profile is reduced by 20% to 40%, due to the stamping.
 14. A process according to claim 7, wherein the thickness of the sheet-metal profile is reduced by 30%, due to the stamping.
 15. A process according to claim 9, wherein the spacing is dimensioned to be between 40% and 60% of the thickness of the sheet-metal profile.
 16. A process according to claim 9, wherein the pre-cutting is performed along the pre-cutting edge, wherein the pre-cutting edge has the spacing is dimensioned to be between 45% and 55% of the thickness of the sheet-metal profile.
 17. A process according to claim 9, wherein the pre-cutting is performed along the pre-cutting edge, wherein the pre-cutting edge has the spacing is dimensioned to be 50% of the thickness of the sheet-metal profile. 